MOSCOW (AP) — Russian politicians accused the United States on Friday of undermining global security by ending compliance with a nuclear arms treaty, while NATO said Russia was at fault for the pact’s demise and European countries watched with dismay.

The U.S. announced it would stop observing the Intermediate-Range Nuclear Forces treaty as of Saturday and would withdraw within six months from the pact, a cornerstone of international security since 1987.

The treaty signed by the United States and the Soviet Union bans the development, deployment and testing of land-based nuclear weapons with a range of 500 to 5,500 kilometers (310-3400 miles). Moscow and Washington have for years traded claims of the other party being in violation.

Before Friday’s announcement, the United States alleged that a new Russian missile breached the treaty. Russia in turn accused the United States of unilaterally seeking to neuter the agreement and of resisting Russian attempts to resolve the dispute.

“I ‘congratulate’ the whole world; the United States has taken another step toward its destruction today,” Konstantin Kosachev, head of the foreign affairs committee in the upper house of Russia’s parliament, said.

Another Russian senator, Igor Morozov, alleged the move “carries a threat to the entire system of international security, but first of all for Russia, because after leaving the INF the Americans will deploy these missiles in European countries,”

However, the end of the treaty could also serve Russia’s strategic interests, removing any obstacle to Moscow deploying intermediate-range missiles that could reach Europe and China.

U.S. officials had expressed worry that China was gaining a significant military advantage in Asia by deploying large numbers of missiles with ranges beyond the treaty’s limit. Leaving the treaty with Russia would allow the United States to counter the Chinese, but it’s unclear how the Pentagon might try to do that.

Washington’s decision was received with anxiety in Europe despite an assertion by the head of NATO that Russia has been in violation of the treaty for several years.

“All NATO allies support the U.S. decision today to start the withdrawal process, but it will take six months before that process is completed,” NATO Secretary General Jens Stoltenberg told The Associated Press in an interview Friday. “We continue, therefore, to call on Russia to come back into compliance and fully respect the INF Treaty.”

Stoltenberg said the Russian missile system at the center of the current dispute “can reach most of Europe, and that’s exactly why European allies are so extremely concerned.”

The Europeans are keen to avoid a repeat of a crisis in 1983, when NATO allies decided to deploy U.S. cruise and Pershing 2 ballistic missiles as negotiations with Moscow faltered over Russia’s stationing of SS-20 missiles in Eastern Europe.

Before word of the U.S. withdrawal came from Washington, European Union foreign policy chief Federica Mogherini called on both countries to stick to the treaty.

“What we definitely don’t want to see is our continent going back to being a battlefield or a place where other superpowers confront themselves,” Mogherini told reporters in Romania.

An independent Russian military analyst, Pavel Felgenhauer, told The Associated Press that in order “not to get the Europeans too angry,” Russia “will deploy (intermediate-range missiles) on a not very quick basis.

“So there most likely will no immediate arms race,” Felgenhauer said.

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Alison Mutler in Bucharest, Lorne Cook and Raf Casert in Brussels, David Rising in Berlin and Danica Kirka in London contributed.